Soil has been shown to be one of the largest carbon reservoirs in terrestrial ecosystems, since in the process of sequestering CO2, it contributes greatly to reducing greenhouse gases.
The doctoral thesis of the researcher from the Department of Agricultural Chemistry, Edaphology and Microbiology of the University of Córdoba, who works within the European project Diverfarming, Manuel González Rosado, has been based on this premise.
The doctor in Soil Science and Agricultural Chemistry explains that the soil of the Mediterranean olive grove has an enormous capacity to sequester carbon since, for many years, bad practices have been used that have led to the loss of CO2, such as conventional tillage or no tillage to herbicide base.
This has led to the fact that very little stabilized carbon has been found in the soil in the Jaén plots where the study was carried out, so there is currently a large storage capacity in this area. «These are soils that have great potential, because there is a lot of storage availability, which gives the opportunity to sequester carbon and make it remain, with the appropriate agricultural practices,» explains González.
Among the management studies that help to sequester carbon is the introduction of green roofs between the streets of the olive grove that, in addition, prevent soil erosion, something that is outlined as one of the main problems of Andalusian olive groves. The UCO researcher explains that, annually, amounts above 10 tons of soil per hectare per year are lost in these crops, especially high when no-tillage practices and bare soil with herbicides are applied. «This could be reversed with the implementation of covers, since erosion could be greatly reduced,» adds González.
For this reason, he considers almost «mandatory» a change in management that implies the inclusion of plant covers and that also increase productivity and promote the regeneration of soil properties by improving them. At the opposite extreme, he points out that conventional tillage practices and no tillage with bare soil are unsustainable to achieve objectives such as those of the ‘4 per 1,000’ initiative, which proposes an increase in soil carbon of 0.4% in the first 40 cm from the ground.
However, his thesis has gone a step further, studying not only this top layer but also the other soil strata. In this way, he considers it very relevant to take into account the deep horizon in carbon storage since the effects vary. «We analyzed complete profiles up to 120 cm deep and we saw that almost 50% of carbon was stored in these lower layers», explains the researcher, indicating that if they had only kept the first 40 cm «the changes would not have been significant. ”.
In fact, the result varies even within the same plot, in a matter of the depth to which it is referred. For this reason, it is important to study the way in which carbon is not only stored, but also in which it is kept in depth, since depending on the fraction of the soil in which the carbon is found, it will have a greater or lesser stability. .